The development of a model reference adaptive controller to control the knee joint of paraplegics

Abstract

Functional neuromuscular stimulation is a technique for restoring motor function by directly activating paralyzed muscles. The design and development of closed-loop controllers that, when used in a simulation system, achieve regulated, repeatable control of the lower limb joints is discussed. Models describing the dynamic behavior of the unloaded lower limb joints under electrical stimulation are described. These models consist of a nonlinear part followed by linear dynamics described by deterministic autoregressive moving average (ARMA) models. These models are used in the design of an adaptive controller to control the movement of the leg joints. Design requirements including a severe constraint on the control rate so as not to excite spastic reflexes, are formulated, and a model reference adaptive controller design which was modified and implemented is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>